This invention relates to a drafting table construction and more particularly to a drawing board readily ajustable to different levels and adjustable to selected inclined positions at each level.
Prior proposed drafting tabel constructions were provided with a drafting board hinged adjacent its front edge to the table frame and providee with arms pivotally connected adjacent the rear edge of the table and adjustably connected with the table frame for raising and lowering the rear edge of the table to adjust the table to a selected inclination. In some instances the table frame and its pivotal connection to the front edge of the drafting board were capable of vertical adjustment to raise the front edge of the drafting board (U.S. Pat. No. 2,215,462). Vertical adjustment of the board and its inclination was provided in a different manner by vertically adjustable front and back legs interconnecting the board with a base (U.S. Pat. No. 2,554,599). Another arrangement of such vertical and angular adjustment of a drawing board with respect to its base is shown in U.S. Pat. Nos. 2,555,575 and 2,877,074. A book support or desk utilizing a hinged series of pawls or arms of unequal length to adjust the neight and to adjust the inclination is shown in U.S. Pat. No. 180,052.
In some prior proposed drafting table constructions, adjustment of the height of the table required several steps, namely first uniformly and evenly raising the table and then securing each of said legs. The securement means included pins inserted into a selected hole or included frictional holding of each leg by tightening a knob to frictionally retain the leg in a selected position. Adjustment of the height of the table by one person was often awkward and time consuming because of binding of the several parts when attempting to uniformly lift both sides of the board and because drafting boards provided with drafting equipment and machines mounted thereon were relatively unbalanced and heavy for one person to handle. Preferably height adjustment was made by two persons, one at each side of the board, so that the board could be uniformly lifted.
It is desirable that a drafting board be conveniently adjustable with respect to height and inclination at each height and that such adjustment be readily made without assistance from another person and preferably in substantially one continuous motion.